it's that many SNEAKING IN ILLEGALLY are criminals.
This is patently false. The criminal rate for immigrants - legal or otherwise - is lower than the American population.
and the crimes are not arrests for smoking pot
This is not accurate either. African Americans are convicted of marijuana possession at a rate of 370% compared to Caucasians.
https://norml.org/marijuana/fact-sheets/item/racial-disparity-in-marijuana-arrests
It's left wing propaganda saying right wing people say that ALL Mexicans are criminals.
I don't know of anyone saying "all Meixicans are criminals." But I do know of at least one person who is saying Mexican Immigrants are criminals:
"When Mexico sends its people, they’re not sending their best. They’re not sending you. They’re sending people that have lots of problems, and they’re bringing those problems with us. They’re bringing drugs. They’re bringing crime. They’re rapists. And some, I assume, are good people . . .They’re sending us not the right people. The U.S. has become a dumping ground for everyone elses problems."
-Donald J. Trump